What does -ea- mean?

-ea- meaning in Etymology Dictionary

digraph introduced early 16c., initially getting the noise of lengthy "a" and meant to distinguish words spelled -e- or -ee- thereupon sound from people that have the noise of long "e"; for instance break, great. Since c.1700, the noise in a few of them has actually drifted to lengthy "e" (review, hear) or sometimes short "e" (bread, wide range).